With the confirmation process for Deputy National Security Advisor John Brennan to be director of the Central Intelligence Agency set to be begin shortly, Sen. Ron Wyden (D-Ore.), a member of the Senate Select Committee on Intelligence, is asking Brennan to provide Congress with the secret legal opinions outlining the government’s ability to target and kill Americans believed to be involved in terrorism.

In a letter to Brennan sent Monday, Wyden reiterated his concerns that the intelligence community, Justice Department and the Administration have not been adequately forthcoming to Congress on their legal justifications for targeting and potentially killing U.S. citizens believed to be involved in terrorism activities.

The senator said it is important that the legal opinions guiding these activities be released so that Congress and the American people can “have full knowledge of how the executive branch understands the limits and boundaries of this authority…”

“For the executive branch to claim that intelligence agencies have the authority to knowingly kill American citizens but refuse to provide Congress with any and all legal opinions that explain the executive branch’s understanding of this authority represents an alarming and indefensible assertion of executive prerogative,” Wyden wrote in the letter.